Method of extracting oils from oleaginous materials



ELEVATOQ R. 0. Bowen L72L686 METHOD OF EXTRACTING OILS FROM OLEAGIHOUSMATERIALS 7 Filed NOV. 22. 1926 2 Sheets-Sheat l GAS Wi;

CONVEYING 1E2.

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BOBERT O. BOYKIN, OF LOS ANGELES, CALIFORNIA, ASIGNOB TO N. RUSSELLVAIL,

LOS ANGELES, CALIFORKIA.

METHOD 01E EXTBACTING OILS FROM OLEAGINOUS MATERIAL? Application filed.November 22, 1926. Serial No. 15,856.

My invention relat s to a process of recovering oil'froui oleaginousmaterial such as cottonseed, soya-bean, copra, fish-meal, and

the like. 5 There are various processes well known in the art forrecovering oiltrom oleaginous material, both of the batch processandcontinuous process. The essentials of these processes consist in firstmixing the oleaginous material, which has been comminutcd into a. meal,with a suitable solvent so that the oil will be absorbed by the solvent.The solvent and oil solution is thiin separated from the meal and theoil is thereafter separated from the solvent.

'My invention has for its broad object to eliminate certain faultsof theordinary processes, and thus provides. process which will bra-recognizedas superior, The most apparent faults oi-the ordinary; processes arethat they are not efficient; thus a certain percentage of oil is notrecovered, and there is an absence of economy which would make theprocessreallyprofitable.

com lishment of the broad object of the-invention is that the oleaginous meal be very thoroughly mixed with .the sol-vent and thatthe-solvent be given ample time to entirely penetrate or permeate tieoleaginous meal sothat the oil .will be thoroughly absorbed by'thesolvent. It is-gan obj a process --of. removing-,3 011...,fromoleaginous mealinwhich oleaginous meal is maintained in contact 'ivith'a,,solventforfa prolonged periodiof'time.

-1-I '.-liavc,formdithat in order to efficiently recover th e maximl mpercentage of oil it is necessary to use solvent in large proportions.

It is an object-of this-invention therefore to provide a' process ofrecovering oil from oleaginous deal-in whicha large proportion ofsolvent isused ,I havediscovered that the solvent used in the recessmustjbe of a low specific gravity, pre erably belojv- -that of water, sothat the mixin thereof with the meal will be easy. If

' the so ventused has a higher specific gravity than that of thermal,the mixing will be dif ficult and unsatisfactory,-thc meal tending Ihave found that one requisite to the acecti nventionto i provide tofioa-t on top of the solvent. Under such circumstances efficientextraction of the oil would not be obtained without using an abnormalquantity of solvent.

solvent evaporates freely in the atmosphere,

by providing an air-tight apparatus, while othershave merely disregardedthe evaporation of the solvent, being contented to suffer the loss.Evaporation of the solvent is an important consideration from the standpoint of economy, and any reduction of solvent losses will decreaseoperating expenses. Experience has taught that it is impossible to makea practical apparatus which is airtight. Consequently such a scheme isnoteflicacious. In my invention I carry on the process in what is knownas an open circuit system and. fill the system. with an inert gas sothat the process is carried on in the'presence of the inertgas. Thesystem is maintained at atmospheric pressure or at a pressure of anounce or so more than atmospheric, so that if any leakage occurs, itwill be the passage of inert gasinto the atmosphere.

It is accordingly one of the objects of the invention to provide aprocess of separating oil from olea inous meal, which process is carriedon in t e presence of aninert gas.

Various other objects and advantages of the invention will be disclosedin the followmg description. v

Referring to the drawings in which I did? grammaticall carrying on t 1eprocess of my invention,

Fig. 1"is an elevational view partly in section of one portion of theapparatus.

Fig. 2 is an elevational view partly in section of the other portionofthe apparatus.

Fig.3 is a fragmentary section of'a filter which forms a part of theapparatus.

Referring in detail to the drawings, 1 is a poidmeter, 2 is an elevator,3 is a drier, 4

illustrate. an apparatus for is an "absorbing t0wer, 5 is a cyclonesepa' is a vacuum pump, 9 is a gas trap, 10 is a' condenser, 11- is aheat exchanger unit, 12

v is a still, 13 is a cooler, 14 is a separator unit,

15 is an emulsion breaker, 16 is a rotary ajn drier, 17 is a condenser,and-18 is a settling tank.

V The poidmeter .1 has an oleaginous mealhopper 20 which is adapted tofeed .meal onto a moving feed belt 21, the feed belt 21 being extendedaround a pair of pulleys 22. The meal is delivered by the feed belt 21to the lower end of the elevator 2. The poidmeter 1 also includes asynchronizing pump 24 which is operated from one of the pulleys 22 bygears 25. The synchronizing pump 24 receives a supply of solvent througha pipe line 26 (Fig. 1). The pipe line 26 is connected to a solvent:feed pump 27 (Fi 2). The pump, 27 is a centrifugal pump and even thoughit operates continuously can only build up acertain pressure; Thepurpose of the pump 27 is, of course, to supply the synchronizing pump24'with a solvent. The synchronizing pump 24 delivers solvent through asolvent feed pipe 29 to the digester 6. The purpose of the poidmeter isto measure the quantities of oleaginous meal and solvent which aredelivered tov the digester. It is desirable to have a certainamount ofmeal and a certain amount of solvent comprising the mixture which isdelivered-from the digester 6 to the rotary filter 7f The elevator 2consists of ahousing 31 which encloses a bucket belt 32, the bucket belt32 extending over sprockets 38 placed at the opposite ends of thehousing 31. The meal is delivered into the lower end of the elevator 2by means of the fed belt 21 and is then carried by the buckets of thebucket belt 32 to the upper end of the housing 3]. where it is deliveredto the drier 3. The

a conduit 35 which connects to ashell 37 of the drier. The drier 3 inactual. practice is quite long so" that the meal will be given ampletime to be dried. 'I'heshell 37 is provided with a steam jacket 38 forheating the interior of the drier,"a .nd the drieris provided' with aworm conveyor 40, for moving I the meal from the left end to therightend of it. An inert gas inlet pipe 42 is con-; nected to the rightend of the drier for ilelivering hot inert gas thereto. The inert gaspasses in a-leftward direction through the drier and passes downwardthrough the' ele- .vator 2.

' The absorbing tower 4 consists of a vertically disposed shell 43having a guiding bafiie 44 to' guide the meal into revolving agitators45 mounted in the shell' 43. I These agitators have a. series of axiallyaligned arms 46 spaced every 90 of rotation and successive agitators areadapted to revolve filter mealis delivered to the drier 3 by means ofshell to which shell 70 the inert gas line drum 71 w 7 drum 71' has a.cylindrical-filteringmedium 47, being driven by crossed belts 48running on pulleys 49 mounted on each agitator; The meal in passingdownward throu h the absorbing tower 4 is retarded, agitate and anycakes are broken by contact with the' arms of the agitators 45.

he cyclone separator 5 consists of a shell 50 havinga tangential inlet51 which is connected to the interior of the absorbing tower 4 slightlyabove the central part thereof. Extending-from the lower endof the shell50 is asolid material drain pipe 53 which is'connected to the extremelower end of the absorbing tower 4; The cyclone separator also has aninert gas passage 54 having a valve 55 and extending totherotary filter7.

The lower end of the absorbing tower 4 is connected'to a worm conveyor57 which delivers the meal to the digester 6.

r The digester 6 consists of a shell '58 provided with bafiies 59,which-divide it into a series of mixing compartments 60. Extendinghorizontally through the digester 6 is a rotatable Shaft 62 to whichagitators 63 are attached. There is an agitator 63 in each compartment60.. Each agitator 63 has paddles 64 which mix the meal and solvent. Itshould be noted that these'paddles 64 are placed parallel to the axis'ofthe shaft 62 so that their action on the meal and solvent 54 from thecyclone separator 5 is connected. Therotaryfilter 7 is essentially astandard Oliverfilter, well known in different arts and particularly inthe art ofseparating oil from 'oleaginous meal. Since the Oliver filteris so well known, it is'unnecessary to go into a'great deal of detail;therefore, in the drawings 1 ;have diagrammatically shown only theessential parts.

- Referrin to the drawings the filter 7 has a fiieh' isrotatablysupported. The

72 which is referably made from afabric of fine mesh. nsidej thefiltering medium 72 is a cylindrical wall 73 which provides anannular'space 74fwhich is divided into sections 'by partitions75.Gonne'cted-to each of-the sections 74 are pipes 77 The pipes .77, asillustrated in Fig. 3, are connected to an end plate 78.. Adapted tooperate against the end v uum pump 8;. ny type of vacuum pump 1 ed tothe gas trap 9..

plate 78 is a valve plate 79. The valve plate the pipes 77 will be inCommunication with the vacuum channel 80, whereas another of the pipes77 will be in communication with the pressure channel 81. The channel 80is in communication with a vacuum pipe 82 which is connected to thevalve plate 7 9. The znixturc pipe 07, as shown in Fig. 2, extends tothe interior of the shell 70 and is adapted to deliver the mixture to areservoir tank 83 of a cake former- This cake former is of a particularconstruction and forms the subject matter of my application for LettersPatent entitled Cake former for continuous rotary filter, Serial No.91,967, filed March 3, 1926. Reference to this application isrecommended. Briefiy, however, 'the cake former has the tank 83 to whichthe mixture is delivered. Carried in the tank 83 is an agitator 81 whichis provided to prevent a settling of the meal from the solvent. Adjacentto the reservoir tank 83 is a distributor 85 which has end plates 86.The bottom of the distributor 85 is open so that the mixture whichpasses thereinto over an overflow wall 87 has direct contact with thefilter medium 72 of the rotary filter. As the drum 71 rotates, a cake isapplied to the drum. p

' Wash solvent is supplied to the cake formed, as just described, bymeans of a plurality of solvent sprays 90. The sprays 90 are connectedby a pipe 91 to a solvent tank 92. The solvent tank 92 has a filtermedium 93 through which the solvent must pass before it can enter thepipe 91. Solvent is supplied to the lower portion of the solvent tank 92by a pipe 9 1.having a flow control valve 95. 'The pipe 94 is connectedto the solvent feed pump 27. It should be noted that the solvent issprayed onto the cake immediately upon its forming and before any gascan be pulled therethrough. J This is important since if an gas ispulled. through the cake it will crac and the subsequent washing willnot be effective. I

. The vacuum e 82 is coimebt'ed to thememay be used but I preferth use arotary exha'uster as shown in the drawings; The rotary exhaustcrconsists of a shell in which a. rotor 101operate's. There is always asealing body 102 of solvent maintained in the pum 8. This type .ofvacuum pump 15' desirab e since it requires no internal lubricationwhichin this case is a'problem in rec1procating pumps; Connected tothe vacuumpump 8 158.11 outlet pipe 103'which is connect- The p s trap 9 is ofstandard construction having-a" b'aflle plate 104 which d rects theingrate is a gress downward. The vacuum pump 8 sucks solventcarryingoil, solvent vapor and a little inert gas from the filter. The liquid ofthe flow delivered to the gas trap passes downward from the gas'trapthrough a solution pipe 105 which is extendedto the heat exchanger unit.The solvent va ors and inert .gas pass from the upper end 0 the gas trap9 through a pipe 107 to the condenser 10.

The condenser 10 may be of any type. The

f0 rm shown in the drawings consists of a shell 108 in which heads 109are placed. Connecting between the heads 109 is a plurality of tubes110. The solvent vapors and inert gas pass into the shell 108' above theupper head 109 and pass through the tubes110. Surrounding the tubes 110is a cooling medium which reduces the temperature of the gas andsolventvapor condensing a greater portion of the solvent. Thecondensates passfrom the lower end of the condenser 10 through a pipe112 to the pipe 105, the pipe 112 having'a check valve 113 preventing areverse flow through the pipe 112. The gases, that is, the solventvapors and the inert gas are conducted by a pipe 115 to the lower partof the absorbmg pors, therefore, ass u ward through the absorbing tower,eing rought into intimate contact therewith. The solvent is absorbed andadsorbed by downward the meal passing through the a sorbing tower,

tower 4. The inert gas and solvent va-' ut the gas 1 passes throughthetangential pipe 51 to the cyclone separator 5. The inert gas carriessome fine particles of-meal which are separatedin the cyclone separator5. The meal particles are returned to the lower end of the absorbingtower by the pipe. 53. The inert gas passes through the pipe 54 to theshell 70.

The heat exchanger unit 11 to which the pipe 105 is connected comprisesa pair of heat exchangers 116. Each heat exchanger 110 1s constructedsimilarly to the condenser :10 having shells 117 which are provided withintermediate heads 119 connected together by tubes 120. The spacesbetween the heads 119 and around the tubes 120 serve as a space for thecooling medium. The pipe 105 is c'on- I ported to the lower part of thecooling space 121 of the right-hand heat exchanger 116. Connected to t eupper part of this space is a ipe 123 whichis connected to the'left-handeat exchanger 116 in communication with the lower part of the coolingspace 121 there-' of. Connected .to the upper partof the eooling spaceof the left-hand heat exchanger .116 is a pipe 124 which extends to thestill 12.

l The still 12 consists of'a shell127 having grate 128 supportednear thelower end thereof. Filled in the-shell 127 above the multiplicity ofshort lengths of pipe 129. The still. is whatis commonly known as aRaschig still. Extending into the shell 127 belowthe grate 128 is asteam Supported below the pipe 134 is a splash plate 135 on which themixture is dropped, it splashing radially outward and thus beingdistributed. The mixture flows downward over the lengths of pipe 129 andis divided into a thin film. Connected to the upper end of the still 12'is a solvent vapor Outlet 137, the inner end of which is provided withan internal separator 138. The solvent vapor pipe 137 is connected to anupper space in the lcftheat exchanger 116 above the intermediate head119. This space is connected to the lower space of this heat exchangerby the tubes 120. Connected to the lower space in the left heatexchanger is a pipe139 which extends to the upper space of the rightheat exchanger 116. The lower space in the right heat exchanger 116 isconnected by a pipe 141 to the cooler 13. The lower space in the, leftheat exchanger 116 isconnected to the pipe 141 bymeans of a pipe 142. pp

The cooler 13 consistsof a shell 143 which encloses a cooling coil 144.The pipe 141 is connected to the cooling coil 144. Cooling fluid, suchas water, is circulated within the shell 143 around the coil 144 bymeans of pipes 146. Connected to the outlet part of the cooling coil 144is a pipe 147.

' the separator unit consists of a mixture of aration takes place.

solvent, Water which is condensed from the steam, and an emulsion ofwater and solvent. The liquid stratifies, as shown in Fig. 2, into threelayers; an upper layer 151 of solvent, a central layer 152 of-emulsion,and a lower layer 153 of water. The solvent in the left separator 149passes through the pipe 150 to the right separator 149. where additionalsep- Solvent' is withdrawn from the right separator 149 by means of a pipe155 which is extended to a solvent storage tank, not shown. Water iswithdrawn from the lower parts of both the separators 149 through a pipe156 having a valve 157.

Placed adjacent to the left separator 149 is an emulsion breaker 15 inthe form of a centrifuge. The centrifuge is connected by means of a pipe158 to the medial portion of the left separator 149 on'the level of thelayer of emulsion.152 so that the emulsion 152 is passed into thecentrifuge 15. In the centrifuge 15 the emulsion is separated into itsconstitut'ent parts, that is, into solventandwash solvent is removedtherefrom by means of the suction placed on the drum through the suctionpipe 82. When the cake reaches the position indicated at X it isloosened from the drum by a blowin action. The blowing action isaccomplished asfollows: An inert gas supply pipe 163 having .a valve 164is connected to the inert gas pipe 54 adjacent to the housing 7 0 of therotary filter. Connected to this pipe 163 above the valve 164 is a pipe.166 having a valve 167. The pipe 166 is con nected to a compressor 168.The compressor 168 is connected bymeans of a pipe 169 to ,a

storage tank 17 0. The storage tank 170 is connected by means of a pipe171 to the valve plate 7 9. The pipe'is connected to the valve plate 79in communication with the channel 81 thereof. lVhen-the pipes 77 moveinto such a position that they communicatewithpthe channel 81, apressure is applied to the sections 74 with which these pipes arecommunicated; therefore, the cakewill be blown from the filter medium72. This blowing action has a loosening effect and makes it easy for thecake to be removed. A scraper 173 engages the periphery of the drum 71where the cake is blown from the drum, removing the cake and directingit into the left end of a worm conveyor 174. The worm'conveyor 174delivers the meal to the upper part of the rotary pan drier 16. j I

The rotary pan drier 16' consists of a shell 176 having a series of pans177 supported therein. These pans 177 are supplied with a heating mediumsuch as steam by means of a pipe 178.; The pans, as shown, provideclosed chambers 180 into which-the steam is delivered. Alternate pans177 have central passages 181 and alternate pans 17 7 have .peripheralpassages 182. Extended vertically through the shell 176 is' a drive.shaft. 184 which supports plows 185. -'The worm conveyor drops the mealonto the u "per pan 177. The shaft 184, which is rotated y means of amotor 187, revolves the plows 185. The plows After the cake passes thenozzles the 185 are so formed as to pull the meal inward towards thecenter of this upper pan. The meal falls through'the central opening 181and drops onto the next pan 17 7. The plows in the next pan are soformed as to move the through a pipe 189 which is connected to the upperpart of the shell 176 and other portions of the solvent vapors arewithdrawn through a pipe 190 which is connected by branches 191 to theinterior of the shell 176 above each of the pans 177. The pipe 190, is

connected to the pipe 189 which extends to the condenser 17. Connectedto the space immediately above the lower. pan 177, which space isdenominated-a steaming space 193, is

a pipe 195 having a valve 196.' The pipe 195 may deliver superheatedsteam or inert gas to the steaming space 193 for the purpose of removingthe last touches of solvent which may remain in the meal.

The meal is withdrawn from the rotary pan drier 16 through a dischargepipe 198 which is connected to. a discharge conveyor 199. The dischargeconveyor 199 is provided with a pipe 200 which is connected by pipes 201to the interior of the conveyor at intervals therealong. Steam issupplied to the conveyor for replacing moisture in the meal which hasbeen removed in the drying process. This replacement of moisture isquite important asit has a preserving effect on the meal and reducesexplosibility thereof. The discharge conveyor 199 delivers the meal 'toa pipe 204 which may downward through a condensate pipe-213 to thesettling tank 18. The solvent vapors which are not condensed pass upwardto the top of the condenser and are withdrawn through a vapor pipe 215.The vapor pipe 215 extends to the lower end of the absorbing tower 4 andthe vapor is passed upward therethrough, being'absorbed by the mealpassing downward in this tower. I

The settling tank 18 consists of a shell 220 into which'the lower end ofthe condensate pipe 213 extends. I The solvent contains a smallpercentage of steam condensateswhich settle in the tank 18, beingwithdrawn through a pi 221. The sol-vent is with drawn from t e upperpart of the shell 220 by a pipe 222 having a valve 223. The pipe 222 isextended andconnected to the pipe 147 which delivers liquid from thecooler 13 to the separatorunit 14. p

The operation 0 the apparatus and the process of the inven ion wi l nowbe described.

In starting u the apparatus, the first op; eration'is to the ent resystem with inert gas. Thil firm, gas may be carbon dioxide,

flue gas consists primarily of carbon dioxide and nitrogen. T Happaratus through the inert'gas'suppl pipe 163 which-is connected toflie' mert gas? e 54 .adjacent to the 811811.701? this time the valve 55is closed. Thevalve 164 is open and the vacuum pump operation. 7 Thevacuum pump 8 draws the flue gas, "that is,

.the inert gas into the'jhell 70, throu h'the drum 71, and the vacuumpipe 82. .T e gas is discharged into the pipe 103 and conducted to thegas trap 9. The mert gas then passes e flue is supplied to the throughthe condenser 10 and through the pipe 115 to the lower end .of theabsorbent tower 4. The inert gas passes upward through thedrier 3 anddownward throughthe elevator 2, emerging from the lower end thereof.When the inert gas flows from the lowerend of the elevator, the valve 55in the inert gas line 54 is opened and cir culation is started throughthe'cyclone separato'r' 5 and the inert gas pipe 54. After thiscirculation has been established, the, valve 167 in the pipe 166 isopened and the compressor 168 is set into operation, establishing a flowof inert gas through this portion of the apparatus. When thiscirculation has been com been expelled from the apparatus, the valve 164in the inert gas supply pipe 163 is partially closed. The system is nowcharged with inert gas and is read to he set into op eration. Variousparts 0 the apparatus are now set into operation.

. Oleaginous material is supplied to the feed belt 21 of the poidmeter lbymeans of the hopper 20 and solvent is supplied to the synchronizingpump 24 of the poidmeter 1 by means of the centrifugal pump 27 Theoleaginous meal may be any organic substance which is pregnant with oil.Oil

meals formed from cottonseel, flaxseed, copra, fish-meal, soyabean, andothers, may used. From a standpoint of efliciency of extraction it isdesirable that the olcaginous meal be ground withcertain limits. I'havefound that the best results are obtained when the meal is ground, asshown, by the follow ing average Tyler Screen analysis:

, Percent. Retained in 10 mesh u-.. 0.5 Retained in 20 mesh.. 10.0Retained in 40 mesh 24.0 Retained in 60 mesh.. 17.0 Passing 60 mesh L;..48.5

It is desirable 'to have the ducal groiiild as specified above so thatthe solvent readily penetrate the meahg Ifthe 18 too c0arse,the solventwill not rea y'mix therewith,' this resulting in a poor pene'm.

tion of the solvent. The following is a list showing approxnnate'speciiie gravities of 95 pleted and it is certain that all of. the airhas different materials which are treated in my 1 into the upper end ofthe absorbing tower 4.

process.

Cottonseed meats (30-40% oil) 1.142 Cottonseed kernels (30-40% oil)1.125 Cottonseed meal (8-10% oil) 1.368 Copra meal (810% oil) 1.135Soya-beanmeal, (ti-8% oil) 1.285

' that the solvent have a low specific gravity preferably below that ofWater. As a solvent I prefer to use benzol C. P. or special;

' solvent naphtha having a specific gravity of 0.725 or a mixture ofbenzol C. P. and special solvent naphtha. Carbon tetrachlorid andsimilar chlorinatedcompounds sufier acrid decomposition and also haveahigh specific gravity in comparison to that of the meal. A

consequent disadvantage is that the meals tend to float on the surfaceof the,solvent having a greater specific gravity than the /efiicientextraction results.

:The meal is delivered to the lower end of meal so that an inefficientmixing and an in-,

the elevatorv and lifted through the elevator by the buckets-thereofthrough the drier 3.

through the solvent feed line 29" to the di-- gester 6. Thesynchronizing pump 24 is synchronized with the feed belt 21 so that aceramount of solvent is supplied to the digester 6 proportionate to theamount of meal delivered to the elevator 2 and subsequentlydelivered tothe di ester 6. I

' In the drier 3 the-meal is relieved of its moisture. The nioisturecontent of the meal, before the solvent treatment, should be reduced aslow as'ipossible, preferablybelow five per cent. This is because of thefact that moisture in. the mixture delivered to the filter -7 forms intoa thick glue with the protein material and clogs the filter medium ofthe rotary filter. The drying action is accomlished by the heating ofthe drier 3 and also y means of a reverse flow o hotiiiert gas which isapplied to the dri r by means of the inert gas pipe 42, after theapparatus is first charged .with inert gas as heretofore explain'cd andbefore the meal is delivered to the drier. Another function of the inertgas is to drive out any air which may be present in the meal." The inertgas flows continuously while the apparatus is in use in a reversedirection through, the drier 3 and the elevator 2 being discharged tothe atmosphere at the lower end.

amaeee The dried meal passes froin the drier 3- The meal drops downwardthrough the ah sorbing tower, being conducted through a tortuous path bymeans of the agitators 45. The meal is brought into intimate contact.with gas and solvent vapor which is introduced into the lower end of theabsorbing tower 4- by means of the pipes 115 and 215. The solvent vaporsof this flow are absorbed by the meal. The meal is then delivered by theworm conveyor 57 to the left compartment 60 of the digester 6. The mealand solvent are'thereafter thoroughly mixed together.

The operation of the digester (i is very important to the process. Itshould he noted that the paddles 64 extend poi-pendiculnrlv to theirplane of movement. The purpose of those paddles is not to move themixture longitudinally along the digester 6 but to move the mixture in acircular path; The mixture of solvent and meal is mixed-to the extentthat any soluble matter is removed from the meal and the meal is keptdnsuspension in the mixture. The movement of the mixture of solvent andmeal longitudinally along the digester 6 is caused entirely by thesupplying of additional meal and solventto the left compartment 60. Whenadditional material is added. the level of the mixture in the leftcompartment 60 rises above the top of the adjacent bafile 59 andoverflows into the adjacent compartment 60. From this it is obviousthatif there were no feeding materhrl rrfl thedigestc therc npnkrtnz nolongitudinal movement of the mixture along the digester. One of the verv, -im-' portant parts of the invention is that the meal and solvent beagitated together for a prolonged'period of time. To obtain anefficientextraction of oil from the meal, the

contact with constant agitation for a period of not less than thirtyminutes. I havefound that an agitation of between thirty minutes and onehour is satisfactoryproviding'the meal corresponds in fineness to theaforementioned approximate srrecn analysis.

The mixture passes from the right compartment 60 through the pipe 67 tothe reservoir tank 83 of the rotary filter 7. The agitating paddles 84operate to prevent a Stratification of the mixture in the reservoir tank83. As the mixture is introduced to the reservoir tank itwill overflowthe'wall 87 and pass into the distributor 8.5 forming a body therein-The constituent parts of the mixture maybe classified as heavyparticles, light-particles,

solvent and meal must remain in intimate Y The very Ell ' drum is asfollows:

- distinct layers.

is pulled onto the filter medium l2 by means 7 of the vacuum placedthereon. The mixture forms the cake, which cake-consists of three beforeany gas can be'drawn therethrough;

wash solvent is sprayed onto the cake.

This wash solvent is taken from the solvent tank b2, as previouslydescribed and as illustrated in Fig. 2- lll ashing the cake .must becarried out carefully and eficiently and V a large amount of washsolvent must be used. As soon as the preliminary solution hasdisappeared from the surface of the cake by the edect' of the vacuumapplied, the wash must be applied. The application of the wash mustbegin before any gas has had time to penetrate or pass through the cakesince the passage of gas through the cake causes it to craclr innumerous places, through which cracksthe wash solvent will pass withoutin reality washing the cake. The wash solvent should be applied as longas the mixture is being fed to the filter and until the oil content ofthe cake has been reduced as low as desired. The average oil content ofthe cake taken at six-inch intervals along the periphery of the materielmaterial Before removing solvent 1. 50% 11. 88% Six inches h'cm lip ordistributor 0.68% I5. 13 Twelve inches from 11p of distributor 0. 41 3.B89? Eighteen Inches from in of distributor D. 31 a 1. 91% TwontyJourinches from lip of distributor. B. 22 1. 34% Thirty-four inches from lipof distributor 0. 19% 0. 93%

oil

The solvent, it should be understood," hos dissolved the oil so that theliquid which is removed from the cake is in the term of a solutionconsisting of solvent and oil. The

' solution passes through the pipes 77 and through the-pipe 82 to thevacuum pumptl.

The suction produced by the vacuum pump, oil course. draws some gas fromthe interior ot the shell 70. Also some of the solvent has changed intoa vapor; For this reason the flow drawn through the pipe 82 consists oithe mixture at oilaud solvent and inert gas and solvent vapors. All thisis delivered from thepurnp 8 through the pipe 103 to the gas trap 9. The.noiuture all oil and solvent passes tron; gas trap 9 throu h the pielllli to the heat exchanger unit l, The inert gas and vapors passthrough the pipe to the condenser lllfw'herle a greater portion'ot theThe .lower'layer is formed tion tower 4'.

solvent vapors are condensed, these condensates passing through the pipe112 to the pipe 105, being conducted with the mixture to the heatexchanger unit 11. The remaining gassous fluids pass upward through thepipe 115 and, as previously explained, are brought into intimate contactwith the incoming meal so that the solvent vapors are absorbed and andsorbed thereby. The flue gas, however, is not absorbed and passesthrough the pipe 51- into the cyclone separator 5. The flue gas carriesfine particles of meal which are separated and returned to the lowerendof the absorbing tower thy means of the pipe 53. The inert gases passthrough the-pipe 54 to the shell 70. It should be noted that the inertgas from the vacuum porn is not dischargeddirectly into the shell 70 atis delivered through the absorbing tower, the cyclone separator 5 andthe pipe 5t. lt has been found impractical to deliver inert gas directlyto the filter shell 70 without first removing solvent vapor. The suddenexpansion oi the vacuum pump exhaust causes ,a precipitation :of fluid.The precipitated fluid becomes aline rain and it wets the final'cake asit is being removed from the drum 71 to the extent that it contains fromto solvent, whereas under proper conditions the content of the cakeshould only be 20% to 25%. lit is for this reason that l prefer todischarge the inert gas and solvent into the base or the absorps Thepassage of gas upward through the tower is very slow under properworking conditions, being about-twenty-five feet per minute.

The solution of oil and solvent delivered to I as a cooling me loan forthe hot vapors passing from the still 12. The solution passes throughtha coolingspace 121 of the right heat exchanger 116 through the pipe123 and through the cooling space 121 of the left heat exchanger 116.The solution absorbs the heat ol the hot vapors and is warm by the timeit passes through the pipe 124'.- and into the pipe llll or the still12.. The solution drops onto the splash late 135 and is diffused 1n theshell 127. he solution is divided into a thin him by the short pipes 129so that it can be efllectivel acted upon by steam intro duced bythesteam. pipe 130. The steam ispreiterably at a pressure of 135 pounds itpassing upward through the still, being roughtinto intimatecontact withthe solu tion'. The solvent oi the solution is vaporiccd and carriedupwardthrough the still withitlio steam. The oi "whiclibolls at a highertern.

perature than thesolvent is not vaporized-but passes j into thelovverpart of the still and withdrawn therel inm by means of an oil talresoll'pi e not. The vuporsol the still must pass t ion h the internalseparator 13d where any liqui" particles are revented from passing intothe pipe 13?. he vapors pass the heat euchan or unit ll is cool and isused through the heat exchangers 116 and the temof the cooler13, beinggreatly reduced in temperature and they are thereafter delivered by thepipe 147 to the separator unit 14. The condensates consist, aspreviously explained, of solvent, water, and an'emulsion of solvent andwater. These three constituents tend to stratify in I the left separatortank 149, as illustrated. The solvent is conducted from the leftseparator tank 149 to the rightsepa- .rator tank 149 where a furtherseparation takes place. The solvent is withdrawn from the rightseparator 149 through a pipe 155 by means of which it is delivered to asolvent storage. Water separated from the mixture is withdrawn from theseparator tank 149 by means of the pipe 156. The emulsion indicated at152 is withdrawn from the left separator tank 149 and delivered to theemulsion breaker where the water and solvent are separated, theseparated solvent being deliv cred by the .pipe 159 to the pipe 155 bymeans of which it is delivered with the other solvent to the storagetank.

Again referring to'the' filter, when the cake reaches the portion of thedrum indicated at X blowing gas loosens it from the drum, as

previously explained, and the .scraper 1'73 removes it from thedrumdelivering it to the worm conveyor 174. The worm conveyor 174 deliversmeal to the rotary pan drier 16. The

' meal at this time has a solvent content of to The meal drops onto theupper pan 1'? 7 and is moved inward thereon by the plows 185'. It passesthrough the central opening 181 and drops onto a lower pan and isconsecutively moved across the following lower pans, by the plowsun'tilit reaches the steaming chamber 193. The drying of the cake from thefilter is best carried out in the no economy is gained from freeing thesolvent by direct steam and then drying out the water with indirectsteam. Practically all the solvent has been vaporized fromthe meal whenit reaches the steamingspace 193. Superheated steam of at least 20Fahrenheit superheat is introduced into the s ace 193 so that the lasttraces of solvent 0 or will he removed. I have found that in place ofusing steam for removing the last traces of solvent odor, inert gas maybe used. The cake is then.

discharged through the pipe 198 into the discharge conveyor 199 wheresteam is introduced through the pipe 200. This introduction of steamsupplies a Water content Whichis desirable for the preservation of themeal and is also desirable inasmuch as it reduces its explosibility. v

The steam and solvent vapors pass through I the pipes189 and 190, aspreviously described,

into the lower space 208 of the condenser 17. p

The vapors pass upward through the condenser and a greater portionthereof is condensed, these condensates consisting of water andsolution. The condensates pass downward through the pipe 213to thesettling tank 18 where the water and solvent separate by stratification.Thewater is withdrawn from the tank 18 through the: pi e 221 and thesolu tion is withdrawn throng the pipe 222, being delivered to the pipe147 and flowing with the'other solution to-the separator unit 14.

The vapors may also have an inert-gas con- 7 stituent if inert gas isemployed in the space 193. A portion of the solvent is not condensed andwill beconducted, with any inert gas, through the pipe 215 tothelowerend of' the absorbing tower 4 where the solvent vapors are absorbed bythe incoming meal,

the inert gas passing into the cyclone sep arator 5.

' It shouldhe understood that instead, of

passing solvent vapor through the absorbing tower 4 from the pipe 115any convenient means for recovering the solvent vapor may be employed,or, its economy of op'eration'is the atmosphere.

In the operation of my invention I keep the valve 164 of the inert gassupply pipe 163 partially open so that inert gas is supplied no factor,the vapors may be discharged into I to the apparatus, thus preventingthe entrance of air and to compensate for inert gas which passes to theatmosphere. My system is essentially an open one, with pressures in thedigester (i slightly above atmospheric due to solvent feed pump 27 andthe synchronized pump 24. Itshould be apparent, however,-

that the digester 6 is in communication with the atmosphere through theabsorbing tower 4, the drier 3, and the elevator 2 which is open to theatmosphere at its base. This pressure slightly above atmospheric permitsa fiow'of inert gases outward in case of a leak rather than permittingair to leak in. Y

I claim as my invention:

1. A process of recovering oil from oleagi nous meal comprising:removing from said menses ture, said solvent dissolving the oil fromsaid meal; distributing said mixture upon a supporting medium; removingthe solution of solvent and oil from said cake; washing'said meal with afresh supply of said solvent; removing the solution of said wash solventand oil from said meal; and separating said oil from said solvent.

2. A process of recovering oil from oleaginous meal comprising: removingfrom said meal .a suflicient proportion of its contained moisture torender it substantially dry; agitating said meal with a water insolubleoil solvent of a specific'gravity not higher than the specific gravityof said meal for not less than onehalf hour, thereby forming a mixture,SLl(lSOl.V6I1l3 dissolving the oil from said meal; distributing saidmixture upon a sup solvent and oil from said meal; washing said cakewith a fresh supply of said solvent; removing the solution of said washsolvent and oil from said meal; separating any solvent vapors from saidsolution; passing said solvent vapors into contact withsaid meal beforeit is mixed with said solvent, said solvent vapors being absorbedthereby; and separating said oil from said solvent.

3. A process of recovering oil from oleaginous meal comprising: removingfrom said meal a suflicient proportion of its contained moisture torender it substantially dry' agitating said meal with a water insolubleoil solvent of a specific gravity not higher than the specific ravity ofsaid meal for not less than one-half hour, thereby forming a mixture,said solvent dissolving the oil from said meal; distributing saidmixture into a cake; removing the solution of solvent and oil from saidmeal; washing said meal with a fresh supply of said solvent immediatelyafter said solution has been removed and before any gas can pass throughsaid meal; removing the solutionof said wash solvent and oil from saidmeal; and separating said oil from said solvent..

4. A process of recovering oil from oleaginousmeal comprising: removingfrom said meal a sufiieient proportion of its contained moisture torender it substan tially dry; agitating said meal with a water insolubleoil solvent of a specific gravity not higher than the specific grav- 1tyof said meal for not less-than one-half hour, thereby forming a mixture,said solvent dissolving the oil from said meal; distributing saidmixture upon a supporting medium; removing the solutionof solventand'oil from said meal; Washing said meal with a fresh supply of saidsolvent immediatel after said solution has been removed and be ore anygas can pass through said meal; removing the solution of sald washsolvent and oil from said meal; separating any solvent vapors from saldsolution; passing said solventvapors into contact with said meal beforeit is mixed with said solvent, said solvent vapors being absorbedthereby; and separating said oil from ,said solvent.

5. A process as defined in claim 1 in which the steps are carried on inthe presence of an inert gas.

6. A process as defined in claim 2 inwhich the steps are carried on inthe presence of an inert gas.

7. A process as defined in claim 3 in which the steps are carried on inthe presence of an inert gas.

8. A process as defined in claim 4 in which the steps are carried on inthe presence of an inert gas.

9. A'process of recovering oil from oleaginous meal comprising: removingfrom said meal a sufiicient proportion of its contained moisture torender it substantially dry; passing an inert gas in con-v ing said .oilfrom said. solvent.

10. A process of recovering oil from oleaginous meal comprising removingfrom said meal a sufficient proportion of its contained moisture torender it substantially dry; passing an inert gas in contact with saidmeal to drive the air therefrom; agitating said meal with a waterinsoluble oil solvent of a specific gravity not higher than the specificgravity of said meal for not'less than one-half hour, thereby forming amixture, said solvent dissolving the oil from said. meal; distributingsaid mixtureupon a supporting medium; removing the solution of solventand oil from said meal; washing said meal with a fresh supply of saidsolvent; removing said washsolvent and 011 from said meal; separatingany solvent vapors from said solution; passing said solvent vapors intocontact with said meal before it 1s mixed with said solvent, saidsolvent vapors being absorbed thereby; and separating said oil from saidsolvent. 11. A process of recovering oil from oleaglnous mealcomprising: removing from sai meal a sufficient proportion of itscontained moisture to render it substantially dry; passing an inert gasin contact with said meal to drive the air therefrom: agitating saidmeal with a water insoluble oil solvent of a specific gravity not higherthan that of said meal for not less than one-half hour, thereby forminga mixture, said solvent dissolving the Oll. from said meal; distributingsaid mixture upon a supporting medium; removing the solution of solventand oil from said meal; washing said meal with a fresh supply of saidsolvent immediately after said solution has been removed and before anygas can pass through said meal; removing the solution of said Washsolvent and oil from said meal; and separating said oil from saidsolvent.

12. A process of recovering oil from oleaginous meal comprising:removing from said meal a suflicient proportion of its containedmoisture to render it substantially dry; agitating said meal with awater insoluble oil solvent of'a specific gravity not higher than thespecific gravity of said meal for not less than one-half hour, therebyforming a mixture, said solvent dissolving the oil from said meal;distributing said mixture upon a porous supporting medium; removing thesolution of solvent and oil from said meal by means of a vacuum; washingsaid meal with a fresh supply of said solvent; removing the solution ofsaid Wash solvent and oil from said meal by means of a vacuum; andseparating said oil from said solvent.

CERTIFICATE OF Patent No. 1,721,686.

ROBERT 0.

13. A process of recovering oil from oleaginous meal comprising:removing from said meal a suflicient proportion of its contained 1;ioistureto render it substantially dry ;passing an inert gas in contactwith said meal to drive the air therefrom; agitating said meal with awater insoluble oil solvent of a specific gravity not higher than thatof said meal for not less than one-half hour, thereby forming a mixture,said solvent dissolving the oil from saidmeal; distributing said mixtureupon a porous supporting medium; removing'the solution of solvent andoil fromsaid meal by means of a vacuum; Washing said: meal with a freshsupply of said solvent; removing the solution of said. wash solvent andoil from said meal by means of a vacuum; and separating said oil fromsaid solvent.

14. A process as-definecl in claim 2 in which said meal is agitatedwhile it is contacted by said solvent vapor.

In testimony whereof, I have hereunto set my hand at Los Angeles,California, this 13th day of November, 1926.

ROBERT o. BOYKIIN.

CORRECTION.

Granted July 23, 1929. to

BOYKIN.

lt is hereby certified that error appears in the printed specificationof the aboi'e numbered patent requiring correction as I. I claims 1 and2 respectively, for the word "cake" read "meal line follows: Page 9,lines 4 and 21,

38, claim 3, strike outthe words "into a cake" and insert instead "uponasupporting medium"; line 114, claim 10, after the word "removing" insertthewords "the solution of"; and that-the said Letters Patent should beread with these corrections therein that the same may conform totherecord of the case in the Patent Office. I

Signed and sealed this 10th day of September, A. D. 1929. 7

(Seal) M. J. Moore, Acting Commissioner of Patents.

